导　　师： 丁士文

学科专业： G0301

授予学位： 硕士

作　　者： ;

机构地区： 河北大学

摘　　要： 电子陶瓷材料是材料科学当中的重要领域，在半导体材料、压电材料、铁电材料、介电材料及绝缘材料等方面都具有广泛应用。钛酸钡是电子陶瓷元器件的基础母体原料，被广泛的应用于制备高介电陶瓷电容器、多层陶瓷电容器、ptc热敏电阻、动态随机存储器等方面，被誉为“电子陶瓷的支柱”。 为了满足高性能介电材料的要求，关键之一就是要实现粉体原料的超细和均匀化。为了获得优异的粉体制备工艺，本研究首先对batio3纯相的合成方法进行了探索。实验中以ticl4，ba(oh)2等无机盐为原料，分别采用常压液相法、水热法和微波液相法合成钛酸钡粉体，并对所合成的粉体进行表征，结果发现：x-射线衍射实验证明，三种方法合成的产品均为立方晶系钙钛矿结构；用透射电子显微镜(tem)测得粉体呈球形，水热法制备的粉体的粒径最大，而微波法制备的粉体的颗粒尺寸与形貌最为优异。本文研究了微波液相法的反应体系的条件，反应物的初始浓度、水解时间、反应时间、物料配比等因素进行了系统优化，并获得了制备高分散纳米batio3粉体的最佳工艺。对三种方法合成的粉体进行制陶实验，并测定其性能。结果发现：由于微波法合成的粉体的颗粒粒径最优异，所以制备出的陶瓷的介电性能得到了显著的提高，而且发现了性能与粒径之间有很强的依赖联系。 但是，由于batio3结构的原因，使其本身存在如下缺陷：1.居里点偏高(120℃)，即在120℃才有最大介电常数值(104)，而室温下的介电常数只有居里点的1/6左右；2.介电损失(tanδ)、温度系数较大。根据理论推测，如果将半径较小的离子取代ba2+，或者将不活泼的离子取代ti4+，都可以使材料的居里峰前移并展宽，介电性能得到改善。另外，陶瓷之所以有别于单晶，在于陶瓷体中有大量晶 Electronic ceramic material is an important field in material science, which is applied to semiconductor, piezoelectricity, dielectric material and insulation material. BaTiO3 as a kind of very important dielectric material, has been widely applied in the production of electric components such as high-property ceramic capacitor, multilayer ceramic capacitor, PTC heat-sensitive resistance, resonance implement, medium amplifier, and is indispensable in electronic industry. Its dosage is largest as capacitor material and basic matrix of electric function ceramic at present. In order to meet the high-capacity need of dielectric material, preparing symmetrical and little-size nanometer powder is the sticking point. In my research work, firstly synthesis methods of pure BaTiO3 were probed to obtain excellent crafts of powder preparation. Nanometer-sized BaTiO3 powders were prepared with inorganic salt, such as TiCl4,Ba/(OH/)2, as raw material by nomal pressure liquid-phase method, water-thermal method and microwave liquid-phase method respectively. Powders synthesized by these three methods were characterized. XRD analysis showed that the powders were cubic provskite structure. The powders are less aggregation and symmetrically ball-like through TEM analysis. The powders synthesized by water-thermal method are larger than those of the other two methods. The size and shape of powders synthesized by microwave method is excellent. Through changing the conditions of reactive system, such as reactant concentration, hydrolysis time, reactant time, material match, the best crafts parameters were obtained, which can prepared small-sized and evenly scattered nanometer BaTiO3 powder. The powders synthesized by the three methods were sintered to ceramic, and mesurate their capability. Because microwave irradiation can synthesize nanometer-sized and evenly scattered powders, the ceramic sintered with them has the better capacity. From the experiment, the relationship of capacity and grain size is determined.

关 键 词： 纳米粉体 介电材料 常压液相法 水热法 微波液相法 钛酸钡 化学掺杂 电子陶瓷材料

领　　域： [电气工程] [一般工业技术] [一般工业技术]